The present invention relates to processing systems for processing workpieces, and more particularly, to high throughput ion implantation systems and methods for implanting workpieces.
Ion implantation has become a standard, commercially accepted technique for introducing conductivity-altering dopants into a workpiece, such as a semiconductor wafer or thin film deposition on a glass substrate, in a controlled and rapid manner. Conventional ion implantation systems include an ion source that ionizes a desired dopant element which is then accelerated to form an ion beam of prescribed energy. This beam is directed at the surface of the workpiece. Typically, the energetic ions of the ion beam penetrate into the bulk of the workpiece and are embedded into the crystalline lattice of the material to form a region of desired conductivity. This ion implantation process is typically performed in a high vacuum, gas-tight process chamber which encases a workpiece handling assembly, a workpiece support assembly, and the ion source. This high vacuum environment prevents dispersion of the ion beam by collisions with gas molecules and also minimizes the risk of contamination of the workpiece by airborne particulates.
The process chamber is typically coupled via a valve assembly with a processing end station. The end station can include an intermediate loadlock chamber or pressure lock which can be pumped down from atmospheric pressure by a vacuum pumping system. The chamber is selectively closed at a downstream end by the valve assembly, which selectively places the loadlock chamber in fluid communication with the process chamber. The loadlock chamber is also coupled at an opposite end to an upstream valve assembly. The end station also includes an end effector which transfers workpieces from one or more workpiece cassettes, through the upstream valve assembly, and into the chamber. Once a workpiece has been loaded into the intermediate chamber by the end effector, the chamber is evacuated via the pumping system to a high vacuum condition compatible with the process chamber. The valve assembly at the downstream end of the intermediate chamber then opens and the workpiece handling assembly mounted within the process chamber removes the workpiece from the intermediate chamber and transfers the workpiece to the support assembly, which supports the workpiece during processing. For example, a loading arm of the workpiece handling assembly removes the workpiece from the intermediate chamber and places it on a platen of the workpiece support structure. The workpiece support then moves the workpiece in the scanning direction past the operating ion source, which implants the workpiece.
A conventional workpiece support structure includes a rotating disc that mounts a plurality of workpieces, or includes a structure for moving the workpiece in a horizontal scanning direction. The multiple movements of the components of the ion implantation system consume valuable processing time, thus reducing the throughput of the system.
Today's burgeoning semiconductor and implantation technology has found widespread acceptance in the marketplace. With this acceptance has come demands for generating large quantities of implanted workpieces at competitive prices. A common goal of most modern implantation systems is to satisfy these demands by increasing the throughput of the system. Presently existing systems, however, are not well suited to meet these manufacturing and cost demands.
Another major problem of present commercial ion implantation systems concerns the costs of operating the facility. Conventional ion implantation systems require relatively large dedicated space and thus have a high associated cost per square foot. Consequently, traditional implantation systems have been relatively expensive to operate.
Hence, there exists a need in the art for improved ion implantation systems and methods that exhibit high throughput, require less floor space, and are more cost efficient to operate. In particular, ion implantation systems that can rapidly process high volumes of workpieces would represent a major improvement in the art.